When you need a replacement screw for an implant abutment, it's important to get the correct one. But that's not always as easy as it sounds.
That's because for most implant systems, there are multiple screws available.
Those design differences include:
-the overall length of the screw
-the length of the head portion of the screw
-the diameter of the head
-the angle of the underside of the head
-distance from the bottom of the head to the implant platform
-distance from the bottom of the head to where the threads start
-the overall threadform, which includes the shape, angle, diameters, and pitch of those threads
That threadform is actually the only constant when looking at different screws for the same platform. That's because the thread design is built into the implant itself. So, any screw that's made to be compatible with a specific implant must have the same threadform as that implant's internal threads. The good news about this is that even if you end up with the wrong screw - as long as it was made for that implant platform, you won't damage the internal threads of the implant by using it.
Every other aspect of the screw design is dependent on the design of the abutment. And this is exactly why there can be so many different screws for the same implant platform.
A big part of this is due to there being multiple manufacturers that make compatible abutments for common implant systems. Atlantis Abutments, for example, makes abutments for all of the major systems including BioHorizons, Dentsply, Nobel, Straumann and ZimVie. And that's just one example, there are many many other abutment manufacturers.
But even if an original abutment is used, that is, an abutment made by the same manufacturer as the implant, there can still be multiple variations. For instance, a stock UCLA abutment might have a different screw design than a CAD titanium abutment.
Let's just use the Straumann Bone Level implant as an example. If we take a look at the RC platform, and just looking at screws sold by Straumann - there are 10 different screws. And even though all 10 of those screws share the same threadform and will therefore thread into an RC implant, they have very different designs. And each of those designs was engineered to work with their specific abutment counterpart.
So, this is why when you call the implant company or your lab and you tell them you need a replacement screw, one of the first questions they'll probably ask is which abutment was used.
If your lab is the one that provided the original abutment for that case, that information should be in their records. If, however, you are using a different lab, the best thing to do is to contact the original lab to determine what abutment was used.
The other option is to try to have your current lab identify the abutment and screw for you. This usually involves removing the abutment and sending both it and the screw to the lab for evaluation. Now, it's not always possible to identify the specific abutment and screw type. In that situation, you'll most likely have to start over with a brand new abutment.
Alex Rugh, CDT
O'Brien Dental Lab
www.obriendentallab.com